Question

why are Asia and Europe called different continents even when they are joint land masses?

Answer 1

As u say the demarcation between Europe and Asia is single land mass but literally saying of different continent ,why because the first map maker( Greece) they thought Asia is a separate continent later on medieval map makers/geographers gave to definition of continents that both including cultural geographers as well as physical geographers .At that time European think that world is flat and only 3 Continent's exciting (Africa/Europa/Asia) this concept of the 3 continents in the old world goes back to classical period.